Pre-Op Tests: Which Blood Work, ECG and Scans Are Needed Before Surgery

A nurse slides a printed list across the desk at the pre-admission clinic: three vials of blood, an ECG, maybe a chest X-ray. The patient, a 44-year-old runner booked for a hernia repair, looks up and asks the question that has been bouncing around social media for months: do I really need all of this?

As of June 2025, pre op tests are having a moment. A September 2024 cardiology guideline update narrowed when an electrocardiogram is worthwhile before non-heart surgery, and short videos claiming that routine blood work is either useless or life-saving have been shared millions of times. Both camps have a point, and both overstate it.

The honest picture, drawn from randomized trials, large observational studies and specialist guidelines, is more interesting than either headline. Which tests help, which ones mostly generate worry, and how your team decides is the subject of this piece.

What changed recently with pre op tests

The most important recent shift came on September 24, 2024, when the American Heart Association, the American College of Cardiology and partner societies published an updated guideline on cardiovascular care around non-cardiac surgery in the journal Circulation. The document says plainly that a routine 12-lead electrocardiogram (ECG, a tracing of the heart’s electrical activity) is not useful for people without symptoms having low-risk procedures, and that routine stress testing before surgery is also not recommended for that group. It leans instead on a simple question: can you climb two flights of stairs or walk briskly up a hill without stopping? That level of effort, roughly four metabolic equivalents (a unit comparing activity to resting energy use), predicts good outcomes better than many tests.

The same guideline gives selective support to a blood marker called natriuretic peptide (a protein the heart releases when it is under strain) for people with known heart disease, older adults, or those with risk factors who are facing larger operations. That is a change in emphasis, not a new mandate for everyone.

A month later, in October 2024, several anesthesia and surgical societies issued joint guidance on the GLP-1 receptor agonist class of medicines used for diabetes and weight management, replacing a blanket instruction with an individualized plan based on the patient and the procedure. If you take one of these medicines, the only safe step is to tell your anesthesia team early and follow their instructions; never adjust it yourself.

Underneath those updates sits a longer trend. The American Society of Anesthesiologists has advised against routine, history-blind testing since its 2012 practice advisory, and its 2013 Choosing Wisely list told clinicians not to order baseline laboratory tests in otherwise healthy patients having low-risk surgery. Britain’s national guidance in 2016 took the same line. The viral debate is new; the evidence behind it is not.

What are pre op tests, and who decides which ones you need?

Pre-operative tests are investigations ordered between the decision to operate and the day of surgery. They exist for four reasons: to confirm you are fit enough for anesthesia, to find problems that would change the surgical plan, to set a baseline against which post-operative changes can be measured, and to satisfy specific safety rules, such as knowing your blood type before an operation that may require transfusion.

Who orders them varies. In many hospitals a pre-admission or pre-anesthesia clinic, staffed by nurses and anesthesia clinicians, runs the process. In others the surgeon’s office handles it, or your primary care clinician is asked to complete a pre-operative assessment. Whoever holds the pen, the method is the same: a structured history (previous anesthetics, heart or lung disease, diabetes, bleeding problems, medicines and supplements, smoking and alcohol use, sleep apnea symptoms) and a physical examination, followed by tests chosen to answer questions that the history raised.

Two scales drive most decisions. The first is surgical risk, usually grouped as low (cataract removal, skin lesion excision, minor hernia repair), intermediate (laparoscopic gallbladder removal, joint replacement) or high (major vascular, chest or abdominal operations). The second is the American Society of Anesthesiologists physical status class, a grade from 1 (healthy) to 5 (not expected to survive without the operation) that summarizes how much illness you carry into the operating room.

Put those two together and the logic becomes clear. A class 1 patient having a low-risk operation sits in the corner of the grid where tests add little. A class 3 patient, say someone with heart failure and diabetes, having a hip replacement sits where tests genuinely shape the anesthetic plan. The list on your printout should reflect where you land, and it is fair to ask your team to explain it.

Which preoperative blood tests are most common, and what each one tells the team

Blood tests dominate most pre-operative lists because a single draw answers several questions at once. The table below summarizes the usual suspects and the kind of patient for whom guidelines consider each one reasonable.

Test	What it measures	Who typically needs it
Complete blood count	Hemoglobin (the oxygen-carrying protein in red cells), white cells, platelets	Intermediate or major surgery, suspected anemia, bleeding history
Kidney function and electrolytes	Creatinine, estimated filtration rate, sodium, potassium	Kidney disease, diabetes, heart disease, diuretic or blood-pressure medicines, planned contrast dye
Blood glucose or HbA1c	Current sugar or the 2–3 month average	Known diabetes, or risk factors with a major operation
Coagulation tests (PT/INR, aPTT)	How quickly blood clots	Anticoagulant use, liver disease, bleeding disorder or unexplained bruising
Type and screen	Blood group and antibodies	Operations with meaningful transfusion risk
Pregnancy test	Pregnancy hormone in urine or blood	Offered, with consent, to anyone who could be pregnant
Liver tests	Enzymes and proteins made by the liver	Known liver disease, heavy alcohol use, certain medicines

The mechanisms matter more than the names. Low hemoglobin reduces the oxygen reaching your heart and brain under anesthesia, so a count that flags anemia weeks before a joint replacement gives time to find and treat the cause. Potassium that is too high or too low makes abnormal heart rhythms more likely while anesthetic drugs are on board. Kidney function governs how fast many anesthetic and pain medicines clear from the body and whether contrast dye is safe. Clotting tests explain bleeding that a careful history has already hinted at; they are poor screening tools when the history is clean.

Most centers accept results from the previous few months if your health has not changed, so recent routine blood work is often reused rather than repeated.

Does everyone need an ECG before surgery?

No, and the 2024 cardiovascular guideline is the clearest statement yet on this point. An ECG is quick and painless: electrodes on the chest and limbs record the heart’s electrical signals for about ten seconds. The question is whether that tracing changes what happens next.

For a person with no cardiac symptoms, no known heart disease and a low-risk operation, the guideline says a routine ECG is not useful. Large observational studies found that abnormalities in this group rarely altered management, while the resulting follow-up appointments and anxiety were real. For people with known coronary artery disease, significant arrhythmia (an irregular heartbeat), structural heart disease or peripheral artery disease who are facing intermediate or high-risk surgery, the same guideline calls a pre-operative ECG reasonable, mainly to provide a baseline that helps interpret any new changes after the operation.

Between those poles sits judgment. Age alone is a weaker trigger than it used to be; what counts is the combination of risk factors, symptoms and the size of the operation. Someone with diabetes, high blood pressure and reduced exercise tolerance heading for major abdominal surgery will usually get a tracing, and sensibly so.

An ECG before surgery also has limits worth understanding. It records the heart at rest for a few seconds, so it can look normal despite narrowed coronary arteries. That is why guidelines ask about functional capacity, the stairs-and-hills question, rather than relying on the tracing alone. Stress testing, in which the heart is monitored during exercise or a drug that mimics exercise, is reserved for people whose results would actually change the plan, for example by prompting a cardiology review before a high-risk operation. Ordering it for a low-risk procedure, the 2024 guideline notes, offers no benefit.

Chest X-rays, echocardiograms and other scans: when imaging actually helps

A generation ago a chest X-ray was part of the pre-operative ritual. That has largely ended, for a simple reason: in people without lung or heart symptoms, abnormal findings that change management turn up in well under 5 percent of films, and the changes they prompt are usually cancellations or extra tests rather than safer operations. Anesthesia guidance now treats the chest X-ray as a test for specific situations: known chronic lung disease, recent respiratory infection, new symptoms such as breathlessness or cough, or planned chest surgery where the surgeon needs the anatomy.

An echocardiogram (an ultrasound scan of the heart’s chambers and valves) sits in a similar category. The 2024 guideline supports it for people with a known or suspected heart murmur, unexplained breathlessness, or heart failure whose condition has changed, particularly before larger operations. It does not recommend it as a screening tool for everyone, because a scan ordered without a clinical question tends to produce incidental findings that are hard to interpret.

Other imaging is almost always tied to the operation itself rather than to anesthesia. A CT scan before abdominal surgery, an MRI before spinal surgery or a Doppler ultrasound before vein surgery map what the surgeon will find. These are planning tools, and your surgeon will explain why each one is needed.

Lung function tests (breathing into a machine that measures airflow and lung volume) are used selectively for people with asthma, chronic obstructive pulmonary disease or planned lung surgery, where the numbers help predict recovery and decide on post-operative monitoring. A sleep study may be requested if screening questions suggest obstructive sleep apnea, a condition in which the airway narrows during sleep, because it changes how airway and pain management are handled.

Do healthy people need pre op tests for minor surgery?

Usually not, and this is where the evidence is strongest. The landmark study is a randomized trial of more than 19,000 people having cataract surgery, published in 2000, which compared routine blood tests and ECG against no routine testing. Complication rates were identical in the two groups, about three events per hundred operations, whether or not the tests were done. A later systematic review by an international evidence group reached the same conclusion for that setting.

Cataract surgery is a short procedure under local anesthetic, so the finding does not transfer automatically to every operation. Large observational studies, however, point the same way for other low-risk procedures: when tests are ordered without a clinical reason, roughly one in a thousand results leads to a change in anesthetic management, while a far larger share leads to repeat tests, delayed surgery or referrals that end in reassurance.

This is the basis for the Choosing Wisely recommendation from the American Society of Anesthesiologists: do not obtain baseline laboratory studies in patients without significant systemic disease having low-risk surgery, and do not order stress tests or chest X-rays routinely in that group. The British national guideline grid takes the same stance, assigning no routine tests to healthy adults having minor or intermediate surgery.

There are sensible exceptions. A pregnancy test should be offered to anyone who could be pregnant, because anesthesia planning and some imaging change in pregnancy. A person who seems healthy but has never had blood work, or who reports fatigue, breathlessness on stairs or heavy periods, may be asked for a blood count because the history is no longer clean. Being told you need no tests is not a sign of a careless clinic. More often, it is a sign of one that read your history and matched the guidelines.

What the evidence actually says, graded by strength

Readers deserve to know not just what the recommendations are but how solid the ground beneath them is. Here is an honest grading.

Strong evidence (randomized trials): Routine testing before cataract surgery does not reduce complications. Two large trials and a systematic review agree, and no credible study contradicts them. This is as close to settled as pre-operative medicine gets.

Moderate evidence (large observational studies): In low-risk surgery generally, abnormal results from tests ordered without a clinical reason rarely change management, and ECG abnormalities in asymptomatic people add little to risk prediction beyond age and clinical history. Functional capacity, the stairs test, predicts cardiac complications reasonably well, with a validated questionnaire improving on a simple yes-or-no question. Natriuretic peptide levels improve risk prediction before major non-cardiac surgery in older or higher-risk patients. These findings come from cohort studies involving tens of thousands of patients, consistent across countries, but they cannot prove that skipping a test is safe in the way a trial can.

Limited evidence (expert opinion and guideline consensus): Which specific tests to order for intermediate-risk patients having intermediate-risk surgery, how long a previous result stays valid, and whether a chest X-ray helps in older adults with no symptoms. Here guidelines differ in detail, and local protocols fill the gaps.

Two points deserve emphasis. First, the absence of trial evidence that a test helps is not the same as proof that it harms; the case against routine testing rests on low yield and real downstream costs in time, worry and delay, not on direct injury. Second, no study supports skipping tests in people with significant heart, lung, kidney or clotting disease having major operations. For them, the baseline measurements are what make safe anesthesia possible, and the debate on social media simply does not apply.

How your health history and the type of operation shape the list

Think of the decision as a grid with the size of the operation along one side and your overall health along the other. Guidelines from anesthesia societies on both sides of the Atlantic are built on this grid, and understanding it turns a mysterious printout into a readable one.

Minor surgery in a healthy adult occupies the empty corner: no routine tests. Move one step along, to intermediate surgery such as a laparoscopic gallbladder removal, and a healthy adult still usually needs nothing beyond a careful history, though some centers add a blood count. Add a chronic condition, and the picture fills in. Kidney disease brings kidney function and electrolytes. Diabetes brings an HbA1c (a measure of average blood sugar over the previous two to three months) because poorly controlled sugar raises infection and wound-healing problems. Heart disease brings an ECG and, for larger operations, possibly a natriuretic peptide level or an echocardiogram if symptoms have changed.

Major surgery fills most of the grid even for healthier people. A blood count and kidney function are near-universal, because blood loss and fluid shifts are expected. A type and screen is standard when transfusion is a realistic possibility. Clotting tests appear if you take anticoagulants or have liver disease.

Age moves things less than many people assume. Being 75 and fit is not in itself a reason for an ECG before a skin procedure, while being 50 with breathlessness on one flight of stairs is a reason for a closer look before a hip replacement. What age does bring is a higher chance of unrecognized conditions, so older adults are more often screened for anemia, kidney function and, increasingly, for frailty and memory problems that affect recovery.

If your list looks longer than the grid predicts, ask. The answer is usually a specific concern from your history, and knowing it makes the test feel purposeful.

Medicines and supplements that change which tests you need

Your medicine list is one of the strongest drivers of pre-operative testing, which is why the clinic will ask you to bring every bottle, including over-the-counter products and supplements, or a photograph of each label.

Blood-thinning medicines are the obvious example. Warfarin-type anticoagulants are monitored with the INR, a standardized measure of clotting time, and the team needs a recent value to plan the operation. Newer direct oral anticoagulants are not reliably measured by routine clotting tests, so kidney function becomes the key result, because it tells the anesthesia team how long the drug lingers. Antiplatelet medicines, often prescribed after a stent, are handled in consultation with the prescribing cardiologist; the 2024 guideline devotes a long section to this, and the decision about continuing or pausing them is never the patient’s to make alone.

Diuretics and blood-pressure medicines prompt electrolyte and kidney checks. Diabetes medicines prompt glucose and HbA1c, and the GLP-1 receptor agonist class, which slows stomach emptying, prompts a specific conversation about fasting and timing because food remaining in the stomach raises the risk of inhaling it during anesthesia. Steroid tablets taken long term raise questions about the body’s stress response and may require a planned supplement around surgery. Lithium, some epilepsy medicines and certain heart-rhythm drugs may need level checks.

Supplements matter too. Fish oil, high-dose vitamin E, ginkgo, garlic and ginseng are all reported to affect bleeding, and St John’s wort interacts with anesthetic drugs. Your team may ask you to stop some of these for a period before surgery; that instruction should come from them, in writing, with a date.

The rule that keeps people safe is simple: disclose everything, change nothing on your own, and get a clear, written plan for each medicine from the prescribing clinician or the anesthesia team.

Preparing for the pre-op appointment: fasting, timing and what to bring

A little preparation makes the pre-admission visit more useful and spares you a return trip for a missing result.

Bring a complete medicine and supplement list, previous ECG tracings or hospital letters if you have them, the name and contact details of any specialist you see, and notes on any previous anesthetic problems in you or a blood relative, since a rare inherited reaction to anesthetic drugs runs in families. If you use a breathing machine for sleep apnea, say so; if you snore loudly and wake unrefreshed, say that too, because the screening questions will ask.

Most blood tests do not require fasting. A glucose test may be requested fasting, and the clinic will tell you if so. An ECG needs nothing from you except a few still minutes; skip oily skin creams on the chest that morning so the electrodes stick. A chest X-ray requires removing jewelry from the neck, and you should mention any possibility of pregnancy before any X-ray.

Timing is a common source of confusion. Tests are usually done two to six weeks before a planned operation, far enough ahead to act on a result, close enough to reflect your current state. Many hospitals accept results from the previous three to six months if your health has not changed; a new symptom, a new diagnosis or a medicine change resets the clock. Ask the clinic what their window is rather than assuming.

Fasting before the operation itself is a separate matter from fasting for tests. Standard anesthesia guidance allows clear fluids until shortly before surgery and asks for a longer gap after solid food, but the exact instructions depend on your procedure and medicines. Follow the written sheet you are given, and if the instructions conflict with something you read online, the sheet wins.

What an abnormal pre-op result means, and what it does not

An unexpected result is one of the most common reasons for a pre-operative phone call, and the first thing to know is that most abnormal results do not cancel surgery. They prompt a conversation.

Reference ranges are set so that about 5 percent of healthy people fall outside them for any single test. Order seven tests and the chance that at least one lands outside the range in a perfectly healthy person rises to roughly one in three. That arithmetic, not hidden disease, explains many mildly abnormal results, and it is one reason guidelines discourage ordering tests without a question in mind.

Some findings do matter and are worth the delay. A hemoglobin well below the normal range before a major operation is a reason to look for the cause and treat it, because anemia going into surgery is linked with higher transfusion rates and slower recovery in observational studies. Potassium outside the safe band, significantly reduced kidney function, a very high blood sugar or an INR far from target are all reasons to pause and correct. An ECG showing a new rhythm problem or signs of a previous heart attack that nobody knew about changes the anesthetic plan and may lead to a cardiology review.

What a result cannot do is predict your personal outcome. A normal ECG does not promise an event-free operation; an abnormal blood count does not mean complications are coming. These are pieces of a risk picture that your anesthesia clinician assembles with your history and examination.

If you receive an abnormal result, ask three questions: does this change the date, does it change the plan, and does it need follow-up after surgery regardless? Clear answers to those turn a worrying letter into a manageable task.

Common myths about pre op tests, corrected

The viral conversation has produced several confident claims. Here is how they hold up against the evidence.

Myth: more tests mean a safer operation. The randomized trial evidence in cataract surgery and the cohort data in other low-risk procedures show no reduction in complications from routine testing. Safety comes from matching tests to your history, not from volume.

Myth: pre-op tests are padding and nobody reads them. Tests ordered for a reason are read and acted on; anemia, kidney impairment and clotting problems found before major surgery genuinely change care. The criticism applies to history-blind ordering, not to targeted testing.

Myth: a normal ECG means your heart is fine. A resting ECG can be normal despite narrowed coronary arteries. That is exactly why guidelines ask about exercise tolerance and symptoms rather than relying on the tracing.

Myth: an abnormal result means your surgery will be cancelled. Most mild abnormalities lead to a repeat test or a note in the chart. Cancellations are reserved for results that would make anesthesia materially less safe.

Myth: if you had a physical last year, you do not need anything. Many centers do reuse recent results, but a new symptom, diagnosis or medicine change means the old numbers no longer describe you.

Myth: you can skip mentioning supplements because they are natural. Several common supplements affect bleeding or interact with anesthetic drugs. Disclosure is a safety issue, not a formality.

Myth: older adults always need a chest X-ray. Age alone is no longer considered a reason for routine chest imaging; symptoms and known lung or heart disease are.

The pattern across these myths is the same: each one treats a test as a ritual rather than as the answer to a question. Ask what question your test is answering, and most of the confusion dissolves.

Special situations: older adults, children, pregnancy, diabetes and sleep apnea

Some groups sit outside the standard grid, and the adjustments are worth knowing.

Older adults are more likely to have unrecognized anemia, reduced kidney function and silent heart disease, so a blood count, kidney tests and, for larger operations, an ECG are more often ordered. Geriatric surgical guidance also recommends screening for frailty (a measure of reduced physical reserve), memory and mood, and nutritional status, because these predict delirium and slow recovery better than any laboratory value. If you or a relative are over 70 and facing major surgery, a short walking-speed or grip-strength test is a sign of a thorough clinic, not an insult.

Children rarely need blood tests before minor surgery. A careful history of bleeding, recent colds and family anesthetic reactions does most of the work, and routine coagulation tests have poor predictive value in children without a bleeding history.

Anyone who could be pregnant should be offered a pregnancy test with consent, because anesthetic planning and the timing of elective surgery change in pregnancy. If you are pregnant and need surgery, obstetric input becomes part of the pre-operative plan.

People with diabetes should expect an HbA1c; very high values before elective surgery are linked with wound infection and other complications in observational studies, and some centers postpone non-urgent operations until control improves, working with the diabetes team rather than the patient alone.

Obstructive sleep apnea, diagnosed or suspected, changes airway management, pain-medicine choices and post-operative monitoring. Screening questionnaires are short and worth answering honestly; a formal sleep study is reserved for cases where the result would change the plan before a major operation.

Smoking does not usually add tests, but it does add a conversation. Stopping well before surgery, with support from the care team, is one of the few interventions that reliably lowers complication rates.

When to see a doctor before your operation

Pre-operative testing works best as a two-way exchange. The clinic asks and measures; you report anything that has changed. Certain signs should prompt a call to your surgical team or primary care clinician before the operation date, and a few warrant emergency care.

Contact your surgical or pre-admission team promptly if, in the weeks before surgery, you notice:

• New breathlessness on effort you used to manage, or needing extra pillows to breathe at night
• Chest tightness or pressure with activity, or an unusually fast, slow or irregular pulse
• Fainting or near-fainting episodes
• Unexplained bruising, bleeding gums, nosebleeds or blood in urine or stool
• A cough, fever, sore throat or other infection within about two weeks of surgery
• New swelling, warmth or pain in one calf
• A fall, a new diagnosis, a new medicine or a change to an existing one
• A letter or call about an abnormal result that you do not understand

Seek emergency care immediately for crushing chest pain, sudden severe breathlessness, one-sided weakness or facial drooping, difficulty speaking, or a severe headache unlike any you have had. These are not pre-operative matters; they are emergencies in their own right.

For everything else, the decision about whether a result or symptom changes your surgery belongs to the surgeon and anesthesia clinician who know your case. They can repeat a test, arrange a specialist review or adjust the plan. What they cannot do is act on information they never receive, so when in doubt, call. A short conversation with the pre-admission nurse is far cheaper in worry than a cancelled operation on the day.

Finally, if you are managing a long-term condition, keep your usual clinician in the loop. Pre-operative tests sometimes surface findings, such as kidney changes or a high HbA1c, that deserve follow-up after the operation whatever happens in theater.

Frequently asked questions

What tests are done before surgery for a healthy adult?

Often none for minor surgery. Guidelines from anesthesia societies advise against routine blood tests, ECGs and chest X-rays in healthy adults having low-risk procedures, because large studies show they rarely change management. For intermediate or major operations, a complete blood count and kidney function tests are common, with a type and screen if transfusion is possible. A pregnancy test is offered to anyone who could be pregnant.

Is pre surgery blood work always required?

No. Blood work is required when your history, medicines or the size of the operation raise a specific question, such as possible anemia before a joint replacement or kidney function before a procedure using contrast dye. Healthy people having short, low-risk operations frequently need no blood tests at all. If you are unsure why a test is on your list, ask the pre-admission team to explain what it is checking.

Why would I need an ECG before surgery if I feel fine?

Usually you would not. The 2024 cardiovascular guideline says a routine ECG is not useful for people without symptoms having low-risk surgery. It becomes reasonable when you have known heart disease, significant risk factors such as diabetes and high blood pressure, or limited exercise tolerance and are facing a larger operation, mainly to provide a baseline tracing for comparison afterward.

How long are pre-op test results valid?

It depends on the hospital and on you. Many centers accept blood results from the previous three to six months and an ECG from the previous six to twelve months, provided your health, symptoms and medicines have not changed. Any new diagnosis, new symptom or medicine change usually means the tests are repeated. Ask the pre-admission clinic for their specific window rather than assuming.

Do I need to fast for preoperative blood tests?

Most pre-operative blood tests do not require fasting. A fasting glucose or lipid test may be requested in some cases, and the clinic will tell you in advance if so. Fasting for the blood draw is separate from fasting before the operation itself, which follows written instructions about when to stop solid food and clear fluids. Follow the sheet you are given for each.

Can an abnormal pre-op result cancel my surgery?

It can, but most abnormal results do not. Mild deviations often lead to a repeat test or a note for the anesthesia team. Results that make anesthesia materially less safe, such as significant anemia, dangerous potassium levels, very high blood sugar or a new heart rhythm problem, may lead to a postponement while the issue is treated. Your surgeon and anesthesia clinician make that call.

Why is a chest X-ray no longer routine before an operation?

Because studies show that in people without lung or heart symptoms, abnormal findings that change management appear in well under 5 percent of films, while incidental findings often trigger further tests and delays. Guidance now reserves the chest X-ray for people with known lung disease, recent respiratory infection, new breathlessness or cough, or planned chest surgery where the surgeon needs the anatomy.

Which medicines should I tell the pre-op clinic about?

All of them, including over-the-counter products and supplements. Blood thinners, antiplatelet medicines, diabetes medicines including the GLP-1 class, diuretics, blood-pressure drugs, long-term steroids and some heart-rhythm or epilepsy medicines all affect which tests are ordered and how anesthesia is planned. Supplements such as fish oil, ginkgo and St John’s wort matter too. Never stop or change a medicine without instructions from your clinician.

Do older adults need extra pre-op tests?

Often some. Older adults are more likely to have unrecognized anemia, reduced kidney function or silent heart disease, so a blood count, kidney tests and sometimes an ECG are ordered more readily before larger operations. Age alone is not a reason for a chest X-ray. Good clinics also screen for frailty, memory and nutrition, which predict recovery better than most laboratory values.

Does a normal ECG mean my heart is safe for surgery?

Not on its own. A resting ECG records a few seconds of electrical activity and can look normal despite narrowed coronary arteries. That is why anesthesia and cardiology guidelines weigh your symptoms, risk factors and functional capacity, such as whether you can climb two flights of stairs without stopping, alongside any tracing. A normal ECG is reassuring, not a guarantee.

References

• MedlinePlus: Tests and visits before surgery
• NHS: Electrocardiogram (ECG)

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.